Cam grinding and marking fixture



p 1952 R. E. SHETLER CAM GRINDING AND MARKING FIXTURE Filed Aug. 17, 1951 mHHHHHH PAY 5. S/EZ'ZZEE IN VEN TOR.

BY 7 4/700/1 [1 j,

Patented Sept. 9, 1952 UNITED s'mrss 2,609,643 ,oAM eamome ANDMARKING FIXTURE Ray E. Shetler, Chula Vista, Calif., assignoito Bohr Aircraft Corporation, Chula Vista, Galifi,

acorporation of California Application August 17, 1951, Serial No. 242,263

"8Glaims. (01.51-432) I I 1 V This invention relates the fixture adapted to mark a cam outline on a workpiece and also to guide a workpiece while a cam face is ground thereon. I An object of the invention is to provide a fixture adapted for marking a cam outline of desired contour on a metallic or nonmetaliic workpiece.

Another object is to provide a fixture adapted for use with an ordinary grinding wheel'to grind a cam on a metallic or nonmetallicworkpiece.

A further object is to provide a fixture which isreadily adjustable for marking cams of widely different contours on different workpieces.

A still further object is to provide a fixture for use with a grinding wheel for grinding cams of different contours on different workpieces.

Another object is to provide a fixture of the type described in which the adjustments for cams of various contours may be easily and quickly made without the use of any special tools.

Further objects will'become apparent as the description of the fixture proceeds. For a better understanding of the invention reference is made -to the accompanying drawings, in which:

Figure 1 is a top view of a cam-grinding and marking fixture embodying the invention also showing a grinding wheel, and

Figure 2 is a section of the fixture shown in Figure l'taken on line 2-2 also showing a work piece in place.

The invention is shown for marking and/or grinding a cam face Iii on a workpiece H which may be cast iron, steel, brass or other metal or it may be composed of hard plastic or other non-metallic material. The workpiece is provided with a central cylindrical bore l2 and a smaller cylindrical bore I3 spaced from bore i2 for a .purpose to be later described. The workpiece is ground on a grinding wheel is fixed tothe end of a shaft l5 which is rotated at a high speed by anysuitable means, such as an electric motor (not shown). It will be understood that the 22, the sidewalls: 23 of the groove iproviding'ifa guideway for guiding the slide ma" direction nor mal to wheel face 20. i

Slide 22 has secured thereto a vertical 'pivot pin 24 on which a cam disc 25 is's'uppor'te'd' for rotation, pin 24 also passing thrOugh bore 'l-Z in the workpiece. Disc 25 is also providedwith an indexing pin 26 which passes throughbore l3 of the workpiece, thus locking the workpiece for rotation with cam disc 25. At equally spaced apart intervals around it's periphery, disc 25 1s provided with a plurality of radially extending bores 2'! which slidingly receive hard' steel'cylindrical pins 28, each of which may be lockediin its adjusted position by a set screw 29"threa'dd into a tapped hole 30 in disc 25. Near its front edge support [6 has an abutment block 3 l"secure'd thereto by a pair of screws -32 which extendinto threaded holes in the support.

A vertical hole 33 is provided near the .rea'ro'f base [9 to receive the supporting {post 34 :of. ='a scribing or marking tool 35, whichmay be'lo'cked at any desired height by a thumb-screw threaded into a tapped hole 31 in plate l9. Near its end tool 35 is provided with a scriberholder 38 in which the scriber 39 is adjustably mounted.

In using the fixture to mark the contourioff'a cam on a workpiece, holes l2 and 13 are bored in workpiece H and pins 28 moved in or outfof holes 2! until their outer ends lie on a .curve the shape of the desired cam. Each pin is locked in place after it is set by its setscrew- 29. In an embodiment ofthe invention; for marking and grinding a cam of the shape illustrated, a series of 50 holes spaced 'LZ degrees apart was drilled in disc 25 and 48 of the-"pins 28 were utilized. Support lfi 'is then moved toits position furthest from the grindingwheel 'and materials of which the grinding wheel is made will be selected in accordance with the material composing the workpiece and the degree of smoothness required on the finished cam face.

The fixture comprises a support 55 along the edges of which extend two parallel slots I? through which pass the shanks of a pair of screws l8 threaded into a fixed base plate It anchored in front of wheel It. The shanks of screws Ill have a close sliding fit in slots H and guide support !6 in a direction normal to the front face 20 of wheel l4. Cut in support It is a groove 2| in which is slidable a cam supporting slide screws l8 tightened. The workpiece His lowered into position, pins 24 and 25 entering-the holes l2 and i3 respectively. Marking'tool 35 is 1'0- tated approximately 180 degrees from its position as shown in Figure 2 and lowered until the point of its scriber it rests on the workpiece, then the thumbscrew 35 is tightened. The workpiece and cam disc 25 are then rotated together in the direction indicated by the arrow. As the end of each pin 28 comes into successive engagement with the face of block 3!, slide 22 is gradually moved rearwardly along guideway 23 and pin 24 approaches stylus 39 causing a cam contour of gradually decreasing radius to be marked on the workpiece. After the workpiece has been marked, it is lifted from the fixture and the excess Inaterial removed by a band saw or other cutting accepts 3 tool, leaving a margin of from .015 to .025 inch outside the marked cam outline. The screws i8 are now loosened and support 16 moved to its extreme forward position, disc 25 rotated to the position shown in Figure 1 and the slightly oversize workpiece put in place, after having rotated marking tool 35 to the position shown in Figure 1. The operator new moves the workpiece along with support l6 and cam disc- 25 towards'grinding wheel l4' without rotating them, grinding away the edge of the workpiece until the highpoint of the cam outline previously scribed has,

been reached. Screws 18 are then tightened to lock support 16 in the operating: position shown;

The-workpiece is then slow-lyr'c'tated in thdi-TEQ? tion shown by the arrow, a slight pressure in? a direction away from the grinding wheel, being maintained on the workpiece to bring the ends" of pins 28 successively into engagement with-block 3|. When the pin which projects furthest from disc:,2.57is: in engagement with and'normal to the face offblock- 31 the cam g-rindingis complete;

This invention may be embodied in-other-Vforms ori carried: out inother ways without departing immerse; spirit or essential characteristics thereof.; The present embodiment of the'inventioir is thereforertor beconsideredas in allrespects illustrative andnot-restrictive', the scope of the invention being indicated'by-thezappended claims and: allchanges which come within themeaning and" range, of equivalency of the claims are-intended: to be embraced; therein.

Having: thus described my invention; what I claimas ne'wand useful and;desire; tosecureby from? rotating with reference to said rotatable member.

Zi A YfiXture as: claimed in claim l-;' inwhich a marking tool issupported with its end in engagement with: the upper-faceof' the workpiece to inscribe: -acam curve thereon: as said rotatable member: is manually rotated-.

3. Ai fixture asclaimed in claim 1;- in which said fixed" support is: provided with avertical guideway; a; marking tool having a portion slidable in-saidguidewa-y and having a sharp tip; and means for securing the tool-atarr elevation in said guideway to? causeitstip to engage the (LII upper face of the workpiece to inscribe a cam curve thereon in response to rotation of said rotatable member.

4. A fixture as claimed in claim 1; in which said rotatable member is provided with a plurality of spaced apart openings; and the inner ends of said pins are seated in said openings.

5'; A33 fixture adapted tdf advance; a; workpiece by a predetermined amount comprising: a support; a slide in engagement with said support; means for guiding said slide in a straight path; a member projecting vertically from said slide; an adjustable radial cam comprising a plurality of-r spaced;- apart pins, said cam being pivotally mounted oh?- saidprojecting member; a rigid member mounted for engagement by said pins successively to; advance the slidealong said path as the" cam is rotated; and indexing means for preventing the workpiece from rotating with reference to said radial c'am.

6:,A-fiXt-ll1'6: as claimedin claim 5; in which said indexing means comprises a member projecting; upward from? said cam-gand the workpiece is provided with an opening to receive said lastv namedmember.- 4

7a..v A fixture as-cl-aimed in claim-5; inwhicha fixed-=baseis provided under; said support; and means is provided for securing said support at a-desiredpositiorr on. said fixed base.

8;-A- fixture adapted to advance a workpiece having v an aperture therein toward the face of a grinding wheel comprising; in combination: a fixedv support having a: groove normal to the face-of the wheel-ineits; upper face; a-,fl at.plate slid-able insaid-groove; a vertical shaft secured to said plate and extending upwardly into. said aperture; a-disc pivotally mounted on saidvshaft, said; disc.- being providedaround its periphery With-a plurality ofradial openings; a, plurality of pins seated in; said openings; I aplurality of set screws arranged to secure saidpins at, such positions in said openings thatthe outer ends of said pins lie along a,- cam curve. of desired contour; rigid member positioned, to, be en gagedby'the ends of said pins successively in response tov the rotation of-said disc; and-index ing means for anchoring the workpiece at a predetermined position on said disc.

REFERENCES. CITED The following references are of record; in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,085,381 De Gianni Jan. 27,, 1914 1,231,920 humsden- July 3, 1917 2387,0751 Johnson Oct. 16, 1945 2,420,547 Lovely May. 13, 1947 

